Cooling system and method of cooling an interior space

ABSTRACT

A cooling system ( 20 ) includes a media exchanger ( 50 ), a cooling section ( 22 ), and a cooling circuit ( 120 ) for circulating a cooling fluid ( 130 ) between the media exchanger ( 50 ) and the cooling section ( 22 ). The media exchanger ( 50 ) receives outside air ( 38 ) and the cooling section ( 22 ) receives return air ( 32 ) from and interior space ( 34 ). When the cooling fluid ( 130 ) circulates into the cooling section ( 22 ) via the cooling circuit ( 120 ), the temperature of the return air ( 32 ) is reduced through indirect heat transfer between the cooling fluid ( 130 ) and the return air ( 32 ) to produce conditioned air ( 84 ). The conditioned air ( 84 ) is provided as supply air ( 46 ) into the interior space ( 34 ). When the cooling fluid circulates into the media exchanger via the cooling circuit, the temperature of the cooling fluid is reduced through direct heat transfer between the cooling fluid and the outside air.

TECHNICAL FIELD OF THE INVENTION

The present invention is a continuation of U.S. patent application Ser.No.: 13/397,170, filed 15 Feb. 2012, which claims priority under 35U.S.C. §119(e) to: “Adiabatic Cooling Unit,” U.S. Provisional Ser. No.61/444,958, filed 21 Feb. 2011, which are incorporated by referenceherein.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to cooling systems. Morespecifically, the present invention relates to high efficiencyeconomizer cooling.

BACKGROUND OF THE INVENTION

A data center is a facility used to house computing systems andassociated components, such as telecommunications and storage systems. Adata center can occupy one room of a building, one or more floors, or anentire building. Most of the equipment is often in the form of serversmounted in cabinets, which are usually placed in single rows formingcorridors (so-called aisles) between them. This allows people access tothe front and rear of each cabinet. The data center typicallyadditionally includes redundant or backup power supplies, redundant datacommunications connections, environmental controls (e.g., airconditioning, fire suppression), and security devices.

Manufacturers of data center equipment continue to increase computecapability while at the same time improving compute efficiency. However,the power consumption of such servers is also rising despite efforts inlow power design of integrated circuits. With the increased powerconsumption comes a commensurate increase in concentrated heat loadsproduced by the servers, network equipment, and storage facilities. Theheat dissipated by this equipment is exhausted into the data centerroom. The heat collectively generated by densely populated racks canhave an adverse effect on the performance and reliability of theequipment in the racks, since the equipment relies on the surroundingair for cooling. In addition to temperature, humidity can have anadverse effect on data center equipment. If the humidity is too high,water may begin to condense on internal components. If the humidity istoo low, static electricity discharge may damage components.

Heating, ventilation, air conditioning (HVAC) systems required tocontrol the temperature and humidity of the data center have beenestimated to account for between twenty five to forty percent of powerusage in data centers. Accordingly, HVAC systems are often an importantpart of the design of an efficient data center. In particular,infrastructure manufacturers and data center designers and operators arefocusing on reducing power consumption from the non-compute part of theoverall power load, which includes the HVAC systems, in order to achievesignificant cost savings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be derived byreferring to the detailed description and claims when considered inconnection with the Figures, wherein like reference numbers refer tosimilar items throughout the Figures, and:

FIG. 1 shows a perspective view of a cooling system in accordance withan embodiment;

FIG. 2 shows, a top view of the coo ling system along section lines 2-2of FIG. 1;

FIG. 3 shows a rear view of the cooling system along section lines 3-3of FIG. 1;

FIG. 4 shows a block diagram of a cooling methodology of the coolingsystem of FIG. 1;

FIG. 5 shows a block diagram of a cooling methodology of the coolingsystem of FIG. 1. in accordance with another embodiment;

FIG. 6 shows a perspective view of a cooling system, in accordance withanother embodiment;

FIG. 7 shows a side diagrammatic view of the cooling system of FIG. 6;and

FIG. 8 shows a top view of the cooling system along section lines 8-8 ofFIG. 6.

DETAILED DESCRIPTION

Embodiments entail a cooling system and methodology for high efficiencycooling of an interior space, such as a data center, warehouse, officebuilding, or any other high heat load facility. In particular, thecooling system and methodology efficiently cool return air from theinterior space and provide the cooled return air as supply air back intothe interior space. Additionally, the cooling system and methodology canprovide a ventilation function, where outside air is mixed with thereturn air on an as needed basis. The mixture of cooled return air andoutside air can than be released into the interior space as the supplyair. The system structural configuration enables a smaller footprint.Additionally, the system and methodology can reduce power consumptionover prior art systems. Accordingly, significant cost savings ears beachieved by utilizing smaller and more efficient cooling systems andmethods that reduce energy use.

FIG. 1 shows a perspective view of a cooling system 20 in accordancewith an embodiment. Cooling system 20 is a heat exchanger system inwhich there is efficient heat transfer from one medium to another. Moreparticularly, cooling system 20 implements a combination of directcontact, in which heat transfer occurs in the absence of a separatingwall, and indirect contact, in which heat transfer occurs across aseparating wall.

Cooling system 20 generally includes a cooling section 22, a mediaexchange section 24, a mixing section 26, and a supply section 28.Cooling section 22 includes an air inlet 30 which is configured toreceive return air 32 from an interior space 34. Media exchange section24 has outside air inlets 36 for receiving outside air 38 (i.e., airthat is external to interior space 34) and outside air outlets 40 fordischarging outside air 38. As will be discussed in detail below,cooling section 22 and media exchange section 24 operate cooperativelyto efficiently cool return air 32. The cooled return air 32 issubsequently released as conditioned air into mixing section 26.

Mixing section 26 also includes outside air inlets 42. At mixing section26, the conditioned air may be mixed with outside air 44 drawn intomixing section 26 via outside air inlets 42 to meet suitabletemperature, humidity, and/or fresh, air requirements. This mixture ofconditioned air and outside air 44 is then released from mixing section26 as supply air 46 into supply section 28 (discussed below). Supply air46 is released back into interior space 34 via a supply air outlet 48 ofsupply section 28. Supply air 46 enters interior space 34 where theprocess load (e.g., heat discharge irons servers, power supplies, andother equipment) in interior space 34 increases the temperature ofsupply air 46. As supply air 46 hears up to a pre-set temperature,supply air 46 enters return air inlet 30 of cooling section 22 as returnair 32 to repeat the cooling process.

It will be observed that different arrow styles are utilized in FIG. 1,as well as the remaining FIGS. 2-5. The different arrow styles areutilized to distinguish various air sources and/or purposes of the airemployed in cooling system 20. For example, return and supply air 32 and44 respectively are represented by block arrows. Outside air 38 enteringand exiting media exchange section 24 is represented by solid arrowheadswith a double-lined shaft. And, outside air 44 entering mixing section26 is represented by single lined arrowheads and shaft. It should beunderstood, however, that return and supply air 32 and 46, respectively,is the air exiting and air entering interior space 34. In contrast, bothoutside air 38 and 44 represents the air entering cooling system 20 fromthe environment external to both cooling system 20 and interior space34. However, outside air 38 and 44 is entering to different sections ofcooling system 20 for different purposes.

In the illustrated embodiment, cooling system 20 is a roof mount unit.Accordingly, return air inlet 30 and supply air outlet 48 are located inthe bottom of cooling system 20. However, in alternative embodiments,cooling system 20 may be configured as top end, or side discharge andreturn configurations. Additionally, cooling section 22, media exchangesection 24, mixing section 26, and supply section 28 are modularcomponents that can be readily configured in accordance with aparticular cooling configuration. Furthermore, cooling section 22 andmedia exchange section 24 are arranged in a slacked configuration toeffectively reduce the footprint of cooling system 20. Thus, coolingsystem 20 can be readily sealed in accordance with particular coolingconstraints for interior space 34.

Referring to FIGS. 2-3, FIG. 2 shows a top view of cooling system 20along section lines 2-2 of FIG. 1, and FIG. 3 shows a rear view ofcooling system 20 along section lines 3-3 of FIG. 1. Thus, FIG. 2represents a top Internal view of cooling section 22, mixing section 26,and supply section 26. Whereas, FIG. 3 represents a rear internal viewof cooling section 22 and media exchange section 24.

As expressly shown in FIG. 3, media exchange section 24 includes a firstmedia exchanger 50 and a second media exchanger 52. First mediaexchanger 50 has outside air inlets 36 and outside air outlets 40. Firstmedia exchanger 50 accepts outside air 38 via a first outside air path54 (denoted by a dashed line). Outside air 38 passes through evaporativemedia 56 located in first media exchanger 50 to one or more fans 58 andis released out of first media exchanger 50 into the atmosphere.Likewise, second media exchanger 52 accepts outside air 38 via a secondoutside air path 60 (also denoted by a dashed line). Outside air 38passes through evaporative media 62 located in second media exchanger 52to one or more fans 64 and is released out of second media exchanger 52into the atmosphere.

Evaporative media 56 and 62 may be formed from a cellulose based paper,flame retardant material, aspen fiber material, or any other materialtypically utilized in evaporative cooling configurations in which waterflowing through the media cools and/or humidifies air flowing throughthe evaporative media. Thus, first and second media exchangers 50 and 52serve as direct exchangers in which heat transfer occurs in the absenceof a separating wall.

Cooling section 22 is physically separated from first and second mediaexchangers 50 and 52, respectively, of media exchange section 24 viasolid walls 66. Cooling section 22 includes a first cooling section,referred to hereinafter as a first cooler 68 and a second coolingsection, referred to hereinafter as a second cooler 70. First cooler 68has return air inlet 30 and a first conditioned air outlet 72. Firstcooler 68 is configured to receive return air 32 from interior space 34via a first return air path 74 (denoted by a dashed line). In anembodiment, first cooler 68 includes a filter 76, which is in line withan indirect exchanger 78, which is likewise in line with a directexchanger 80. Accordingly, when return air 32 is received at returninlet 30 of first cooler 68, return air 32 in first return air path 74passes through filter 76, indirect exchanger 78, and direct exchanger 80to produce conditioned air 84 which is output from first conditioned airoutlet 72.

Likewise, second cooler 70 has return air inlet 30 and a secondconditioned air outlet 86. Second cooler 70 is configured to receivereturn air 32 from interior space 34 via a second return air path 88(denoted by a dashed line). In an embodiment, second cooler 70 includesa filter 90, which is in line with an indirect exchanger 92, which islikewise in line with a direct exchanger 94. Accordingly, when returnair 32 is received at return inlet 30 of second cooler 70, return, air32 in second return air path 88 passes through filter 90, indirectexchanger 92, and direct exchanger 94 to produce conditioned air 84which is output from second conditioned air outlet 86. First and secondcoolers 68 and 70 generally cool return air 32 to produce conditionedair 84. The cooling methodology implemented through the cooperativeoperation of cooling section 22 and media exchange section 24 will bediscussed below in connection with FIGS. 4 and 5.

a diffusion chamber 96 is in communication with each of first and secondconditioned air outlets 72 and 86, respectively. More particularly,diffusion chamber 96 is interposed between first and second conditionedair outlets 72 and 86. Accordingly, conditioned air 84 in each of firstand second return air paths 74 and 88 oppose one another as conditionedair 84 enters diffusion chamber 96. Although conditioned air 84 in eachof air paths 74 and 88 is represented by a single arrow, it should beunderstood that first and second conditioned air outlets 72 and 86 areformed as large as possible to enable a suitable and largelyunobstructed flow of conditioned air 84 from respective first and secondcoolers 68 and 70 into diffusion chamber 96.

Diffusion chamber 96 includes a chamber outlet 98 located at an end ofdiffusion chamber 96 and oriented approximately perpendicular to firstand second conditioned air outlets 72 and 86. A diffusion baffle 100 islocated at chamber outlet 98. In an embodiment, diffusion baffle 100 isa tapered structure having a base 102 and an apex 104. Base 102 islocated in chamber outlet 98, and apex 104 extends into diffusionchamber 96.

Diffusion baffle 100 includes a plurality of openings through whichconditioned air 84 exits diffusion chamber 96. Openings 106 in diffusionbaffle 100 located proximate apex 104 are larger in diameter thanopenings 108 in diffusion baffle located proximate base 102. The taperedshape of diffusion baffle 100 and the arrangement of diameters ofopenings 106 and 108 facilitate the uniform flow of conditioned air 84in diffusion chamber 96 and exiting diffusion chamber 96 via chamberoutlet 98. This uniform flow serves to balance air flow through thecomponents of first and second coolers 68 and 70 to achieve moreeffective beat exchange.

In the illustrated embodiment, diffusion baffle 100 includes twodifferent sizes of openings 106 and 108. However, it should beunderstood that there may be more than two different sizes of openings,with the larger openings being located closer to apex 104 and thesmaller openings being located closes to base 102. Moreover, theopenings need not be circular, but may instead be oval, rectangulartriangular, or any other suitable shape. Additionally, the openings indiffusion baffle 100 may be adjustable through the implementation of amovable plate or valves to control the flow of conditioned air throughdiffusion baffle 100.

Mixing section 26 includes a conditioned air inlet 110 in fluidcommunication with first and second conditioned air outlets 72 and 86.More particularly, conditioned air 84 flowing out of first and secondconditioned air outlets 72 and 86, into diffusion chamber 96, throughdiffusion baffle 100, and out of chamber outlet 98 flows into mixingsection 26 via conditioned air inlet 110. In an embodiment, conditionedair inlet 110 may include a directional louver structure 112 configuredto admit conditioned air 84 into mixing section 26. Directional louverstructure 112 can include slats that diffuse or otherwise spreadconditioned air 84 outwardly into mixing section 26.

In an embodiment, conditioned air 84 in mixing section 26 may blend withoutside air 44 entering mixing section 26 via outside air inlets 42 tomeet suitable temperature, humidity, and/or fresh air requirements forsupply air 46. Outside air inlets 42 may include adjustable dampers,vanes, louvers, or other structure that may be manually or automaticallyadjusted to admit a suitable flow of outside air 44, or alternatively,to prevent entry of outside air 44 into mixing section 26 when outsideair conditions are not suitable. The mixture of conditioned air 84 andoutside air 44 may subsequently pass through a filter 114 located Inmixing section 26 in order to filter dust and/or other contaminants thatmay have entered mixing section 26. Conditioned air 84 then passes outof mixing section 26 and into supply section 28 via fans 116. By way ofexample, fans 116 pull conditioned air 84 out of mixing section 26 assupply air 46. This supply air 46 is subsequently released info interiorspace 34 via supply air outlet 48.

FIG. 4 shows a block diagram of the cooling methodology of coolingsystem 20 of FIG. 1. The cooling methodology is described in connectionwith first cooler 68 of cooling section 22 and first media exchanger 50of media exchange section 24. However, the following discussion appliesequivalently to second cooler 70 (FIG. 3) of cooling section 22 andsecond media exchanger 52 (FIG. 3) of media exchange section 24. Firstcooler 68 and first media exchanger 50 function cooperatively as an aircooler to reduce the temperature of return air 32 entering coolingsection 22. The temperature reduction in first cooler 68 is done usingthe heat in outside air 38 entering first media exchanger 50, thusenhancing the efficiency of cooling system 20.

First cooler 68 generally includes return air inlet 30, filter 76 (FIGS.2-3), indirect exchanger 78, direct exchanger 80, and first conditionedair outlet 72. First media exchanger 50 generally includes outside airinlets 36, evaporative media 56, fans 58, and outside air outlets 40.Cooling system 20 further includes a cooling circuit 120, a sump 122(e.g., a basin or reservoir), a pump 124, a first flow control valve126, and a second flow control valve 128.

In accordance with a method of cooling return air 32, pump 124 pumps acooling fluid 130 from sump 122 through cooling circuit 120 to indirectexchanger 78. In an embodiment, cooling fluid 130 is water. However,those skilled in the art will recognize that other heat transportingfluids may alternatively be used. Indirect exchanger 78 is a heatexchanger having a cooling fluid input 132 and a cooling fluid output134, and is sometimes referred to as a coil. Indirect exchanger 78 isconfigured to transfer heat between return air 32 in first return airpath 74 and cooling fluid 130 to alter the temperature of return air 32in first return air path 74. In particular, return air 32 in firstreturn air path 74 transfers its heat to cooling fluid 130, so thatreturn air 32 cools and cooling fluid 130 heats in indirect exchanger78. By way of example, cooling fluid 130 flowing through indirectexchanger 78 may remove the sensible beat from return air 32 by twentyto thirty degrees, or more. There is no contact between cooling fluid130 and return air 32 while return air 32 passes through indirectexchanger 78. Thus, return air 32 passing through indirect exchanger 78is indirectly cooled.

From indirect exchanger 78, cooling fluid 130 flows within coolingcircuit 120 through first flow control valve 126 to first mediaexchanger 50. First media exchanger 50, and more specifically,evaporative media 56, is a heat exchanger that transfers beat betweencooling fluid 130 and outside air 38 in first outside air path 54. Thisheat transfer function is performed to alter the temperature of coolingfluid 130. Cooling fluid 130 enters evaporative media 56 at a mediaexchanger input 136, flows through evaporative media 56, and exitsevaporative media 56 at a media exchanger output 138. There is directcontact between cooling fluid 130 and outside air 38 flowing throughevaporative media 56 via first outside air path 54. As outside air 38passes through evaporative media 56, most of the sensible heat (i.e.,heat exchanged by a body that has as its sole effect a change oftemperature) that is in outside air 38 is turned into latent heat (i.e.,the heat absorbed or released during a change of phase at constanttemperature and pressure). In addition, sensible heat is transferredfrom cooling fluid 130 to outside air 38 in first media exchanger 50.Outside air 38 containing the latent heat and the heat absorbed fromcooling fluid 130 above the wet bulb temperature is discharged fromoutside air outlets 40 via fans 58.

In an embodiment, direct contact between cooling fluid 130 and outsideair 38 reduces the dry bulb temperature of cooling fluid 130 to withinapproximately one to two degrees of wet bulb temperature. The dry bulbtemperature is the temperature of a fluid as measured by a standardthermometer freely exposed to the fluid but shielded from radiation andmoisture. The dry bulb temperature does not indicate the amount ofmoisture in the fluid. In contrast, the wet bulb temperature is thelowest temperature that can be obtained by evaporating water into theair. It is the wet bulb temperature of outside air 38 that permitsoutside air 38 in first outside air path 54, having the same or lowertemperature as return air 32 in first return air path 74, to reduce thetemperature of cooling fluid 130.

In one embodiment, first return air path 74 passes through directexchanger 80 after passing through indirect exchanger 78. Directexchanger 80 is heat exchanger that transfers heat between return air 32in the first return air path 74 and cooling fluid 130 to further alterthe temperature of return air 32 in first return air path 74. Unlike inindirect exchanger 78, there is contact between cooling fluid 130 andreturn air 32 in first return air path 74 while return air 32 passesthrough direct exchanger 80, thus altering the humidity level of returnair 32 in first return air path 74. To that end, cooling fluid 130 flowsfrom first media exchanger 50 in cooling circuit 120 to direct exchanger80 before returning to sump 122. By using direct exchanger 80, thetemperature of return air 32 in first return air path 74 may be broughtto a lower level than the temperature was after indirect exchanger 78.However, the humidity level of return air 32 in first return air path 74is increased when return air 32 passes through direct exchanger 80, asreturn air 32 comes in direct contact with cooling fluid 130. Return air32 in return air path 74 then passes out of first conditioned air outlet72 of first cooler 68 as conditioned air 84.

In some embodiments, direct exchanger 80 may not be utilized. Whendirect exchanger is not utilized, cooling fluid 130 flows from firstmedia exchanger 50 in cooling circuit 120 and returns to sump 122through, for example, a return pip (not shown). As such, the temperatureof conditioned air 84 produced by first cooler 68 will only be loweredby indirect exchanger 78, but the humidity of conditioned air 84 willnot be increased.

Cooling system 20 may include additional features, not illustratedherein for simplicity. For example, cooling system 20 may include aflush line (not shown) that directs the flow of cooling fluid 130 fromcooling circuit 120 directly to sump 122. The flush line can travelalong the top of evaporative media 56, directly contacting the surfaceof evaporative media 56. This permits cooling fluid 130 that flowsthrough the flush line to flush out any debris that may be collectedalong the top surface of evaporative media 56. A flush valve (not shown)can be placed on the flush line to regulate when cooling fluid 130 flowsthrough the flush line. Periodically, the flush valve may be opened sothat cooling fluid 130 flows through the flush line, and the surface ofevaporative media 56 is cleared of debris. Cooling fluid 130 that flowsthrough the flush line can aid in removing any debris that may obstructthe flow through first media exchanger 50. The flush line can empty intosump 122, returning cooling fluid 130 to be recirculated through coolingcircuit 120. The flush valve may be opened periodically (e.g., hourly)to effectively remove debris, as needed.

As mentioned above, first and second flow control valves 126 and 128 areinline with cooling circuit 120. First flow control valve 126 controlsthe flow of cooling fluid 130 from indirect exchanger 78 to first mediaexchanger 50. As cooling fluid 130 flows through indirect exchanger 78,cooling fluid 130 is heated by return air 32 in first return air path74. The flow of this heated cooling fluid 130 to first media exchanger50 can be regulated by first flow control valve 126, thus partiallyregulating the level of flow and temperature of cooling fluid 130 thatenters first media exchanger 50. Second flow control valve 128 controlsthe flow of cooling fluid 130 directly from sump 122. In someembodiments, cooling circuit 120 is configured to permit cooling fluid130 to flow either indirectly to first media exchanger 50, by way ofindirect exchanger 78, or directly first media exchanger 50. Second flowcontrol valve 128 regulates the flow of cooling fluid 130 flowingdirectly to first media exchanger 50.

By controlling the flow through both first and second flow controlvalves 126 and 128, cooling fluid 130 from indirect exchanger 78 ismixed with cooling fluid 130 directly from sump 122 as cooling fluid 130enters evaporative media 56 of first media exchanger 50 for further heatexchange. By changing the flow through first or second flow controlvalves 126 or 128, the temperature of cooling fluid 130 that entersfirst media exchanger 50 can be altered. In addition, by regulating theamount of cooling fluid 130 that flows into first media exchanger 50,first and second flow control valves 126 and 128 affect the temperatureof cooling fluid 130 in sump 122. This is because the temperature ofcooling fluid 130 in sump 122 will decrease if a larger amount of cooledCooling fluid 130 enters sump 122. Regulating the temperature of coolingfluid 130 in this way also regulates the temperature of cooling fluid130 that enters indirect exchanger 78, thus regulating tile amount ofheat energy that must be transferred in indirect exchanger 78 toultimately regulate the temperature of return air 32 in first return airpath 74.

FIG. 5 shows a block diagram of the cooling methodology of coolingsystem 20 in accordance with another embodiment. Again, the coolingmethodology is described in connection with first cooler 68 of coolingsection 22 and first media exchanger 50 of media exchange section 24.However, the following discussion applies equivalently to second cooler70 (FIG. 3) of cooling section 22 and second media exchanger 52 (FIG. 3)of media exchange section 24. First cooler 68 and first media exchanger50 function cooperatively as an air cooler to reduce the temperature ofthe return air 32 entering cooling section 22. The temperature reductionin first cooler 68 is done using the heat in outside air 38 enteringfirst media exchanger 50, thus enhancing the efficiency of coolingsystem 20. In addition, first cooler 68 includes a refrigerant-baseddirect expansion cooling unit 140, such as a direct expansion coolingunit, and a direct cooler 142 in line with indirect exchanger 78. Thecooling methodology represented in FIG. 5 that includes refrigerantbased cooling unit 140 and direct cooler 142 may be utilized to coolreturn air 32 at times when outside air 38 may be too hot and/or toohumid for indirect exchanger 78 to effectively cool cooling fluid 130,and subsequently cool return air 32.

In accordance with a method of cooling return air 32, pump 124 pumps acooling fluid 130 from sump 122 through cooling circuit 120 to indirectexchanger 78. Return air 32 in first return air path 74 transfers itsheat to cooling fluid 130, so that return air 32 cools and cooling fluid130 heats in indirect exchanger 78. From indirect exchanger 78, coolingfluid 130 flows within cooling circuit 120 and enters evaporative media56 of first media exchanger 50. As outside air 38 passes throughevaporative media 56 heat is transferred from cooling fluid 130 tooutside air 38 in first media exchanger 50 and outside air 38 isdischarged from outside air outlets 40 via fans 58.

In the illustrated embodiment, cooling fluid 130 flows from first mediaexchanger 50 in cooling circuit 120 and returns to sump 122. However,return air 32 in first return air path 74 passes through refrigerantbased cooling unit 140 after passing through indirect exchanger 78.Cooling unit 140 cools return air 32 by directly passing return air 32over an evaporator in which refrigerant absorbs heat in return air 32.By using refrigerant based cooling unit 140, the temperature of returnair 32 in first return air path 74 is brought to a lower level than thetemperature was after indirect exchanger 78. However, the humidity levelof return air 32 in first return air path 74 does not change when returnair 32 passes through cooling unit 140. Return air 32 in first returnair path 74 then passes out of first conditioned air outlet 72 of firstcooler 68 as conditioned air 84.

Return air 32 may then pass through direct cooler 142 to further coolreturn air 32. In an embodiment, direct cooler 142 is a directevaporative cooler. As such, a second pump 144 is in line with a secondloop 146 of cooling circuit 120. Second pump 144 circulates coolingfluid 130 through second loop 146 of cooling circuit 120 from sump 120to direct evaporative cooler 142 from which cooling fluid 130 returns tosump 120. Indirect cooler 78, refrigerant based cooling unit 140, and/ordirect evaporative cooler 142 may be suitably controlled to obtain highefficiency cooling in under a variety of environmental conditions.

Although the second stage cooling configuration of FIG. 5 is representedby both refrigerant based cooling unit 140 and direct evaporative cooler142, it should be understood that alternative embodiments may includeonly one of refrigerant based cooling unit 140 and direct evaporativecooler 142, a chilled water cooling unit, or some combination thereof.Accordingly, the cooling capability of such a cooling system can beadjusted to cool the final delivered air, i.e., supply air 46 (FIG. 1)as the web bulb temperature of outside air 38 (FIG. 1) rises and fallsduring operation.

Referring now to FIGS. 6-8, FIG. 6 shows a perspective view of a coolingsystem 150 in accordance with another embodiment. FIG. 7 shows a sidediagrammatic view of cooling system 150, and FIG. 8 shows a top view ofcooling system 150 along section lines 8-8 of FIG. 6. In the abovepresented embodiment, cooling system 20 (FIG. 1) is illustrated as beinga roof mount unit. Cooling system 150 is presented with an end dischargeand return configuration suitable for a ground mount design.Accordingly, return air inlet 30 and supply air outlet 48 are located atan end of cooling system 150.

Cooling system 150 includes cooling section 22, media exchange section24, mixing section 26, and supply section 28, with cooling section 22and media exchange section 24 being arranged in a stacked configuration.In addition, cooling system 150 includes first media exchanger 50,second media exchanger 52, a first cooling section, i.e., first cooler68, and a second cooling section, i.e., second cooler 70, as discussed,above. A detailed description of first media exchanger 50, second mediaexchanger 52, first cooler 68, and second cooler 70 will not be repeatedherein for brevity.

In contrast to cooling system 20 (FIG. 1), however, cooling system 150does not include diffusion chamber 96 (FIG. 2). Instead, cooling system150 includes a return air duct 152 to which return air inlet 30 iscoupled, and an inlet chamber 154 interposed between first and second,coolers 68 and 70, respectively. That is, in this ground mount design,the space between first and second coolers 68 and 70 that was formerlydiffusion chamber 96 now functions as inlet chamber 154.

Inlet chamber 154 is configured to receive return air 32 from interiorspace 34 via a return air path 156 directed from return air inlet 30,through return air duct 152 and into inlet chamber 154. A portion of thereceived return air 32 enters first cooler 68 via a first return airinlet 158 and another portion of the received return air 32 enterssecond cooler 70 via a second return air inlet 160. First and secondcoolers 68 and 70 may be suitably configured as discussed above inconnection with FIG. 4 to include filters 76, 90, indirect heatexchangers 78, 92, and direct heat exchangers 80, 90. Alternatively,first and second coolers 68 and 70 may be suitably configured asdiscussed above in connection with FIG. 5 to include filters 76, 90,indirect heat exchangers 78, 92, refrigerant based cooling unit 140, anddirect evaporative cooler 142.

Return air 32 is cooled to produce conditioned air 84 which is outputfrom first and second conditioned air outlets 162 and 164 ofcorresponding first and second coolers 68 and 70. Conditioned air 84 isreleased into mixing section 26 where it may be mixed with outside air44 as needed. Fans 116 then pull conditioned air 84 out of mixingsection 26 as supply air 46. This supply air 46 is subsequently releasedinto interior space 34 via supply air outlet 48.

The components, e.g., filters, heat exchangers, and the like, areillustrated in FIG. 8 as being angled or suitably canted to provide auniform surface for passage of return air 32. In addition, theindividual components, e.g., filters, heat exchangers, and the like, arerearranged opposite to those shown in cooling system 20 since return air32 flows in the opposite direction through cooling section 22 of coolingsystem 150 relative to the flow of return air 32 through cooling section22 of cooling system 20 (FIG. 1). Cooling system 150 may also be readilyadapted to include a diffusion baffle resembling, for example, diffusionbaffle 100 (FIG. 2), a louver structure resembling, for example,directional louver structure 112 (FIG. 2), and so forth for the purposesdescribed above.

In summary, embodiments entail a cooling system and methodology for highefficiency cooling of an interior space, such as a data center,warehouse, office building, or any other suitable location. The coolingsystem and methodology efficiently cool return air from the interiorspace and provide the cooled return air as supply air back into theinterior space. In particular, the cooling system and methodology employa configuration of indirect and direct heat transfer in whichcirculating cooling fluid may be utilized to cool the return air viaindirect heat transfer (and optionally direct heat transfer). Outsideair is then utilized to cool the heated cooling fluid through directheat transfer. The cooling system and methodology can mix outside airwith the return air on an as needed basis. The mixture of cooled returnair and outside air can than be released into the interior space as thesupply air. The system and methodology can reduce power consumption overprior art systems. Additionally, the stacked configuration of the mediaexchanger and its associated cooler unit enables a smaller footprint,and the modular sections allow for single inlet small versions, as wellas multiple inlet larger capacity versions. Accordingly, significantcost savings can be achieved by utilizing smaller and more efficientcooling systems and methods that reduce energy use.

Although the preferred embodiments of the invention have beenillustrated and described in detail, it will be readily apparent tothose skilled in the art that various modifications may be made thereinwithout departing from the spirit of the invention or from the scope ofthe appended claims. For example, the system can be adapted to includemore or less stages of cooling and or may include a dehumidificationmode. In addition, various mathematical and intuitive techniques can beused for determining size and configuration of a particular coolingsystem, size of evaporative media, which stage of cooling may beimplemented in response to temperature and humidity conditions, size andquantity of openings in the diffusion baffle, and so forth.

What is claimed is:
 1. A cooling system comprising: a first mediaexchanger having an outside air inlet and an outside air outlet saidfirst media exchanger receiving outside air at said outside air inletvia an outside air path; a first cooling section having a first returnair inlet and a first conditioned air outlet, said first cooling sectionbeing configured to receive return air at said first return air inletfrom an interior space via a return air path; a first cooling circuitfor circulating a cooling fluid between said first cooling section andsaid first media exchanger, wherein when said cooling fluid circulatesinto said first cooling section, said first cooling section reduces atemperature of said return air in said return air path with said coolingfluid to produce conditioned air and outputs said conditioned air fromsaid first conditioned air outlet, and when said cooling fluidcirculates into said first media exchanger, said first media exchangercools said cooling fluid in said first cooling circuit with said outsideair and releases said outside air in said first air path from saidcooling system; a second media exchanger having a second outside airinlet and a second outside air outlet, said second media exchangerreceiving said outside air at said second outside air inlet via a secondoutside air path; a second cooling section having a second return airinlet and a second conditioned air outlet; an inlet chamber interposedbetween said first and second cooling sections, said inlet chamber beingconfigured to receive said return air from said interior space via saidreturn air path, wherein a first portion of said return air enters saidfirst cooling section via said first return air inlet and a secondportion of said return air enters said second cooling section via saidsecond return air inlet; and a second cooling circuit for circulatingsaid cooling fluid between said second cooling a second cooling circuitfor circulating said cooling fluid between said second cooling sectionand said second media exchanger, wherein when said second cooling fluidcirculates into said second cooling section, said second cooling sectionreduces said temperature of said return air in said second coolingsection with said cooling fluid to produce said conditioned air andoutputs said conditioned air from said second conditioned air outlet,and when said cooling fluid circulates into said second media exchanger,said second media exchanger cools said cooling fluid in said secondcooling circuit with said outside air and releases said outside air insaid second outside air path from said cooling system.
 2. A method forcooling air entering an interior space comprising: receiving outside airat a media exchanger of a cooling system via an outside air path;receiving return air from said interior space at a cooling section ofsaid cooling system via a return air path, circulating a cooling fluidthrough a cooling circuit from a sump to said cooling section, then tosaid media exchanger, and returning to said sump; exchanging heatbetween said cooling fluid and said return air in said cooling sectionto reduce a temperature of said return air in said return air path andproduce conditioned air; exchanging said heat between said cooling fluidand said outside air in said media exchanger to cool said cooling fluid;releasing said outside air from said cooling system via said outside airpath, and outputting said conditioned air from said cooling section assupply air into said interior space via said second air path.
 3. Amethod as claimed in claim 2 wherein said cooling system includes anindirect exchanger, and said method further comprises: enabling at leasta portion of said cooling fluid to pass through a direct exchanger inline with said indirect exchanger; and exchanging said heat between saidportion of said cooling fluid passing through said direct exchanger andsaid return air to further reduce a temperature of said return air insaid return air path and produce said conditioned air.
 4. A method asclaimed in claim 2 wherein: said outputting operation releases saidconditioned air into a mixing section of said cooling system; receivingsaid outside air in said mixing section; mixing said outside air withsaid conditioned air in said mixing section to produce supply air; andreleasing said supply air into said interior space.